Embedded spring cushion construction



pril 21, 1959 H."J. BURKART EMBEDDED SPRING CUSHION CONSTRUCTION F L1ed July 9, 1956 I a c/a c United States Patent ENIBEDDED SPRING CUSHION CONSTRUCTION Harry J. Burkart, Kirkwood, Mo., assignor to F. Burkart Manufacturing Company, St. Louis, Mo., a corporation of Missouri Application July 9, 1956, Serial No. 596,682

3 Claims. (Cl. 155-179) This invention relates generally to cushion constructions and more particularly to improvements in cushions having embedded springs.

' vIn the past many cushion constructions with and Without .springs have been provided, but modern man constantly demands increased comfort. To this'end the present invention is directed to improvements in cushion constructions, obviating the disadvantages in prior art cushions and ultimately providing a resilient cushion in which increased comfort and long life are assured. Foam or sponge rubber, which have become generic designations for such cushion materials as polyester, urethane, polyurethane, vinyl and isocyanate foams and other resilient compositions, has long been used as a preferred material for cushions. Such foam material cushions are economicah'easy to mold into any given shape, and retain their natural elastic or resilient properties for a long time as compared with other conventional fibrous materials such as cotton, felt, kapok, horsehair and the like. On the other hand, foam materials are so yieldable that compression is completed almost instantaneously and the supporting surface is felt therethrough, this characteristic of foam materials being referred to in the art as bottoming. Furthermore, foam materials slowly lose their molded shape and assume a permanent set.

Cushion constructions having a plurality of spaced springs have also been provided in the past, the springs ordinarily being interconnected or tied together to prevent misalignment thereof during use. These springs have been embedded in solid blocks of foam materials or more often a pad of cushion material has been positioned on a conventional spring base. However, none of the spring cushion constructions has been entirely satisfactory inasmuch as loss of resiliency results in sagging or permanent set, which is further accentuated by the fact that the loads imposed on certain springs or areas of the cushion causes the sagging of adjacent cushion areas due to the interconnections of the springs. Breakage of tie rods and the like of course results in displaced springs and ruptured cushion material. In short, prior art cushion constructions employing foam materials and springs have been unsatisfactory heretofore. The principal object of the present invention is to provide an improved cushion construction which is compressible gradually to prevent bottoming. Another 'object is to provide a cushion that maintains its shape for along period of time. Another object is to provide a cushion'having embedded springs which are maintained in fixed spaced relation without tie means, and which are prevented from becoming displaced by the association of the cushion material therewith. Still another object is to provide an improved cushion in which individual spring action is provided so that load concentration is facilitated and adjacent springs and cushion surface areas are not greatly affected whereby permanent set is reduced to a minimum and usable cushion life is enhanced. Another object is to provide a cushion construction that is lighter, softer and thinner than prior art cushions so that it is particularly adaptable for use in automobiles.

and aircraft. A still further object is to provide a novel cushion construction that is economically and simply manufactured, and greatly improved in comfort and usable life.

These and other objects and advantages will become apparent hereinafter.

Briefly, the present invention comprises a cushion construction including a foam material body provided with a plurality of spaced cavities, and springs embedded in,

the body in circumscribing relationship with a plurality of said cavities.

The invention also consists in the parts and in the ar-' Fig. 4 is a greatly enlarged fragmentary sectional view of the cushion construction, and Fig. 5 is a perspective view of a typical coil spring that may be used in the present cushion construction.

Referring now to the drawings, it will be seen that a cushion construction embodying the present invention comprises a cushion body 10 having a flat unbroken upper surface 11 and a perforated flat lower surface 12 with substantially vertical side walls 13 therebetween. The cushion body 10 may be of any desirable configuration or shape, a substantially rectangular bodyhavingY been shown only for purposes of illustration. The cash-' ion body 10 is constructed of any suitable foam material to provide a cushion having great resiliency.

A plurality of spaced cavities 14 are formed in the cushion body 10 substantially normal or perpendicular to the upper and lower surfaces '11 and 12, and extend from the lower surface 12 toward the upper surfacell.

Each of the cavities 14 has an open end l5formed inthe lower surface 12 and an end wall 16 spaced from. the upper surface 11 by a portion of the cushion body 10 to be described hereinafter. Each of the cavities is provided with a side wall 17 extending between the opening 15 and the end Wall 16, the side wall 17 preferably being continuous and conterminous with the periphery of both the opening 15 and end wall 16. As shown in the drawings, the cross-sectional shape of the side walls 17 may be circular so that cylindrical cavities are provided.

A coil spring 18 is embedded in the cushion body 10 in circumscribing relation with each of the cavities 14. The springs 18 may be of any suitable shape, but are' preferably helicals (Fig. 5) having an intermediate portion 19 including substantially two full turns or coils 20', j

a lower portion 21 having one full turn or coil 22 and an upper portion 23 havinga full outer turn 24 and a 7 partial inner turn 25. The outer and inner turns 24;an d,= 25 of the upper portion 23 are formed ina spiral, and;

the lower and upper end portions 21 and 23 are formed .on spaced parallel planes perpendicular or normal to the axis of the spring 18. The turns of the intermediate and lower portions 19 and 21 define a cylinder having a slightly larger diameter than the side wall 17 of each cavity 14. However, the outer turn 24 of the spiral upper end portion 23 is slightly larger than the cylinder defined by the intermediate and lower portions 19 and 21, and the inner turn 25 is smaller than this cylinder.

The coils of the intermediate and lower portions 19 Patented Apr. 21,

and 21 of the springs 18 are embedded in the cushion Referring to Fig. 4, it will be seen that for purposes of disclosure the cushion body has been divided into different areas 28, 29, 30 and 31 to more fully describe the relationship and coaction between the cushion body 10, the cavities 14 and the springs 18.

The area 28 is defined by the upper surface 11 and a plane a--a (shown in phantom lines), the plane a-a extending through the cushion body 10 above but immediately adjacent to the upper end portions 23 of the springs 18. The area 29 is contiguous With the area 28 -and is defined by the plane a-a and a plane bb (shown in phantom lines), which extends through the cushion body 10 on substantially the same plane as the end walls 16 of the cavities 14. Accordingly, the plane bb is below but immediately adjacent to the upper end portions 23 of the springs 18, and these end portions 23 are embedded in the area 29 in position to support the area 28.

A plurality of areas 30 are provided, each of which comprises a cylindrical tube or layer defined by the side wall 17 of one of the cavities 14 and a cylinder c-c (shown in phantom lines). The cylinder c-c circumscribes the intermediate and lower portions 19 and 21 of the spring 18 so that these portions of the springs are positioned in each of the areas 30. The remaining area 31 of the cushion body 10 is positioned between the plane b-b and the lower surface 12 and in contiguous circumscribing relationship with each of the areas 30.

It is now apparent that the present invention is embodied in a cushion body 10 having a plurality of spaced cavities 14 each of which is circumscribed by a coil spring 18 embedded in the cushion body, and each of the springs 18 having a spiral upper end portion 23 embedded in the cushion body in predetermined spaced relation with the upper surface 11 of the cushion body. The compression characteristics of the cushion body 10 will now be described.

The natural resiliency of the foam material 10 of which the body 10 is constructed is enhanced by the provision of the cavities 14 so that compression thereof would be substantially effortless. However, the springs 18 exert a force in opposition to the compression of the body 10 so that the combination of embedded springs 18 with the foam material slows down compression and prevents bottoming of the cushion body and yet provides a substantially fully compressible cushion.

When the cushion body 10 is subjected to a load, the area 28 at the upper surface 11 is compressed immediately thereby providing a soft feel to the cushion. The spiral coplanar turns 24 and 25 of the upper end portions 23 of the springs provides an improved supporting means for the area 28 to further reduce the feel of the springs 18 at the upper surface 11 of the cushion. The compression 1 of the areas 30 and 31 between the plane bb and the lower surface 12 takes place following the compression of the area 28, the compression of the areas 30 and 31 being comparatively slow because of the resistance of the springs 18 to compression. Accordingly, in the present cushion construction there is no shock imparted to the load as when either a firm cushion is contacted or a foam cushion bottoms, but a smooth settling action is provided.

The springs 18 are prevented from moving laterally in the cushion body 10 primarily by the area 31 thereby obviating the need for tie rods as are used in conventionalspring cushion constructions. The relationship of the springs 18 with the cavities 14 also provides a novel result in that the cohesion of foam material in the areas 30 with the material in the area 31 maintains the springs 18 in fixed spaced relation and in circumscribing relation with the cavities 14; and also in that the cavities 14 provide space for the displacement of the cushion body material between the turns of the springs 18 during compression of the cushion body 10. The possibility of ruptured cushion material is minimized inasmuch as the springs are completely embedded in the cushion body 10.

The springs 18, in addition to preventing bottoming of the foam body 10, coact therewith to reduce permanent set or sag which occurs in conventional cushion constructions. Furthermore, the present cushion provides substantially independent spring action so that loads are concentrated and adjacent areas of the cushion body are not greatly affected by the loads. The compression characteristics of the present cushion construction provide a softer cushion without bottoming and a lighter, thinner cushion especially adapted for automotive or aircraft use. The cushion is also cooler because of the cavities 14.

It is to be understood that the foregoing description and the accompanying drawings have been given only by way of illustration and example, and that changes and modifications in the present disclosure, which will be readily apparent to all skilled in the art are contemplated single coil spring having a body portion embedded in saidbody in circumscribing relationship with each of said cavities, each of said springs also having an end portion including first and second substantially planar end turns embedded in the layer of body material in spaced relation with the end wall of the cavity and the first surface of said cushion body, said foam-like material being compressible around and between said end turns of said spring.

2. The cushion construction according to claim 1 wherein said cavities extend substantially normal to the first and second surfaces, and the first and second end turns of each spring form a spiral end portion in a plane substantially parallel with the first surface, each of thesprings being in spaced relationship with the other springs.

3. The cushion construction according to claim 1 wherein the first turn of the end portion of the spring is larger than the body portion of said spring and the second turn of the end portion is smaller than the body portion of said spring.

References Cited in the file of this patent UNITED STATES PATENTS 1,725,479 Rissman Aug. 20, 1929 2,194,569 Rumpf Mar. 26, 1940 2,247,543 Bernstein July 1, 1941 2,415,765 Schmidt Feb. 11, 1947 

